Fuselage construction



March 29, 1932. J. LEDWINKA ET'AL FUSELAGE CONSTRUCTION Filed Feb. "I. 1930 3 sheets-sheet 1 HVVENTORS. JOSEPH LEDWINKA 6..

FICLZ.

EA m. J. W-Q'AhsoALk. B Y I A TTORNEY.

Filed Feb. '7, 1930 3 Sheets-Sheet 2 INVENTORS. JOSEPH .L'E'DWINKA 6. 5y EARL. 1W. RAG SDALE'.

March 29, 1932 .1. LEDWINKA ET AL March 29, 1932. J. LEDWINKA ET AL FUSELAGE CONSTRUCTI ON Filed Feb. '7, 1930 3 Sheets-Sheet FIG. 8

1X1 'ENTORS JosEPu LEDwm| A a EARL 1W. AGSDALE,

A TTORXE tion employed to a large extent and to an al- Patented -Mar. 29 1932 UNITED STATES PATENT OFF-ICE JOSEPH LED'WINKA, OF PHILADELPHIA, AND EARL J. W. RAGSDALE, OF NOBRISTOWN, -PENNSYLYANIA, ASSIGNORS TO EDWARD G. BUDD HANUI'ACTUBING 60., OFPHILA- DELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA rosnnaen cons'rnnc'non Application filed l ebruary 7, 1980 Serial llo. 428,479.

Our invention has especially to do with the monocoque type of body as applied to aircraft work, but without doubt, it has other applications, adaptations to other types of bodies, adaptations perhaps in other arts;

Adequate strength and lightness, and adequate adaptabilityto the innumerable variations in form of suchbodies and to economical and quantity production have been extremely difficult to attain. This has been due to difliculties inherent in the type of construcmost equally large extent to the lack of ex tended and commercially available forms and material which could be utilized for the purpose. In the manufacture of monocoque bodies of wood, extremely heavy laminated stock is used to make the bulkheads, the bulkheads being sawed to the ring form and appropriately located. The coverings in such case have been either of laminated or strip stock relatively thin, in some cases wrapped about the bulkheads and nailed and glued in place and inothers preliminarily die pressed under appropriate conditions of heat and moisture to the form required by the longitudinally varying perimeter of the body, being thereafter secured by nailing and glumg to the bulkheads.

In metallic such constructions the bulkheads are formed of sheet metal and have been materially lightened and strengthened in such process throughappropriate flanging ofthe sheet metal from which they are made. Metal coverin s for such bodies, however, have presente some of the very difiiculties present in the wooden coverings and other difiiculties akin to them, the wrapping and the die forming processes. Moreover, the strengths of such metal bodies when sufficiently light have been very diflicult to attain and maintain.

The outstanding object of our invention is to construct a monocoque body of metal, particularly of duralumin, which may be made more than amply strong and yet very light, to attain strength in ratios in advance of any attained heretofore. Its further object is to manufacture economically and under- "modern quantity production methods.

'ter. -The corrugations are each of a transofarcuate form, of uniform radius through- At the same time we aim to increase the aerodynamic efliciency of this type of body. Our

inventipn consists not only of the structure but also of the method. A a The structure consists of an interior framework, the bulkheads, the perimeter of which varies throughout the length of the body, and i of a covering therefor longitudinally corrugated throughout its length. Each corrugation extends the full length of the body and is of a width varied as the perimeter of the body varies along its length. In other words, they are tapering and the width'of the taper varies with the variation is the body perimeverse cross section of uniform general cross sectional form, but varying in the extent of their cross section as the perimeter of the body varies. From the exterior the corrugations are predominantly concave. The covering is secured to the bulkheads by resting their bottom upon and securing them to the bulkheads. Specifically, the corrugations are out their length-but of a cross section varying in arcuate extent in proportion to the variation in the body perimeter with the length of the body. v

According to our method, We stretch flat sheet metal stock, duralumin, over a form of'the general contour of the portion of the body to which the covering is tobe applied and also its corrugations, longitudinally roll the corrugations in the material while so stretched to contour, remove it from-the form,

heat treat itand then apply and secure it to the bulkheads. v

The best form of our invention now known to us is the one shown in the accompanying drawings of which Figure 1 is a general three quarter perspective taken substantially in the horizontal plane of such body with the fore part of the body broken away as shown in transverse cross section of the bulkhead.

Figure 2 is an enlarged portion of a transverse cross section such as appears at the left end of Fig. 1.

Figure 3 is a diagrammatic illustration of the varying cross section of the corrugation with the length of the body.

Figure 4 is a rear end elevation of the body.

Figure 5 is a plan view.

Figure 6 is aside elevation.

Figure 7 is a longitudinal vertical section of an arch press used to carry out the method of our invention.

Figure 8 is an end elevation of the same.

Figure 9 is a general three quarter perspective view of the die of the press.

Figure 10 is a diagrammatic illustration of the application of the roll in the process of rollin the corrugations into the paneling.

In t e drawings the transverse y disposed bulkheads of the interior framework are designated 10. There are as usual a series of them from front to rear of the body, of a erimeter which Varies with the length of the ody and gives it its torpedo-like shape. These bulkheads are made of sheet metal preferably by blanking the fiat sheet stock to form a closed figure of the desired form and then flanging up its edges to give it the channel cross section indicated. Suitable holes are provided in the body of the channel section for lightening it up and for the passage therethrough of control connections and the like. These ring-like bulkheads may be formed of other stock than sheet metal stock, if desired, as for example, channel section strip stock bent to pro er form having its ends appropriately joined.

The sheet metal covering is designated in general 11. It envelopes the frames and constitutes not only covering but the longitudinal strength elements of the body itself in accordance with the general principle of monocoque body construction. It is secured to the individual frames and spaces them apart.

This covering 11 is longitudinally corrugated around the entire body. The corrugations extend from end to end of the body or that longitudinal section thereof which is constructed according to the monocoque principle. The corrugations entirely around the body are of identical cross section, in this case of uniform arcuate cross section as clearly appears in Figs. 1 and 3. Fig. 3 is a diagram of one corrugation in its longitudinal extent showing cross sections between its margins at various stations along its length and indicating them all to be of a constant radius K. But the width of the corrugation and hence the length of the transverse cross section is varied from station to station in roportion to the variation of the body along its length.

This treatment of the corrugation enables them to be manufactured economically irrespective of their varying width. Thus, corrugations narrowing toward the tail end of the aircraft body, as clearly appears in Figs. 1, 5 and 6, are as readily available for use as cheaply as those of uniform width. So

available, they render it ossible to narrow the bodies toward the tai thereof as clearl appears in Figs. 4, 5 and 6 and to have each corrugation represented at the tail of the body. The construction of Figs. 1, 4, 5 and 6 is that of a body which terminates in a vertically extending tail post 12. The readiness with which the corrugations are brought to the tail post is at once apparent. Over and above contributing to economy of production, this contributes greatly to appearance but still more and more important] to strength since each corru ation is carrie through the entire length 0 the body or of that section of the body treated and each constitutes a complete longitudinal strength element of the body. Such multiplied strength elements moreover interbrace each other throughout their extent by virtue of their integral jomder at the apexes 13 of the corrugations. 9

The metal covering 11 is secured to the interior framework 10 by means 14 connecting the bottoms of the corrugations with the perimetral flanges of the interior frame-- work 10. The formation of the metal between one fastening 14 and the next adjacent is transversely triangulated in general form. This still further increases the strength. Seat-ing of the fastening means 14 in the bottoms of the corrugations porvides an extent of seatin of the covering 11 upon the frames 10 an a firmness of inter-seating between these parts and the fastening means 14- which is unexcelled. Other forms of fastening means may be used if desired, as for example, spot welding. That shown is riveting. Yet otherforms of headed fastenings may be used.

The method of constructing the body to which the structure lends itself is as unique as the structure itself. It is illustrated in connection with a showing of the apparatus used to carry out the method appearing in Figs. 7 to 9 and in the diagram of Fig. 10. The flat sheet metal stock of which the covering 11 is to be made is stretched over a form 15 by means of end clamps 16. The form in this case is shown as a wooden form but it may be of metal or other material. The form is of the general contour of the surface it is desired to give the aircraft body. It is provided in its face with depressions 17 corresponding in form and number to the form and number of the corrugations desired. This appears clearly in Fig. 9. The clamping device is, in this case, in the form of a heavy are shaped bendable rod borne down into a groove 18 in clamping heads 19 by means of nuts 20 threaded on to its opposite ends after their passage through the transverse beam 21 of the bottom of the clamping head 19. In general form the shapes of the upper peripheries of the head 19 containing groove 18 conform somewhat to the general form of transverse cross section of the body adjacent the point of application. Die 15 and the devices 16 to 21 are commonly swivelly supported on axes 22 borne in base blocks 23 so that the form may be swivelly adjusted about its general lon 'tudinal axis of development. A longitu inally movable transversely extending shaft 24: overlies the form. In its central portion it bears a roller 25 having a perimeter of a transverse cross section conforming to the arcuate cross section of the corrugations. This roller may rotate upon the shaft or rotate with it in case the shaft is rotatable in its longitudinal move ment. Weights 26 of adjustable proportions disposed laterally of the form 15 are hung from the opposite ends of the shaft and bear the roller 25 down upon the metal of the covering 11 with sufiicient pressure to roll the corrugations in when the metal of covering 11 is appropriately tensioned by the clamping devices 16. For this purpose one head 19 is axially adjustable on guides 27 in entirety by screws 27. Y

This apparatus enables the method to be very simply racticed indeed, by simply laying a sheet 0 flat stock or stock approximately preformed to general contour over the top of the die 15, engaging its ends under previously loosened clamping devices 16, drawing the clamping devices firmly down upon the ends by means of the nuts 20, stretching the body of the metal longitudinally by running up tensioning screws 27 to the appropriate degree, to condition the metal of covering 11 by the stretching to take the set of the general contour of the die 15 and to condition the metal moreover to receive and retain the corrugations as longitudinally rolled therein by the longitudinal travel of the 'roller 15, and thereupon longitudinally progrossing the roller 25 back and forth over the stretched surface of the metal 11, first down and up one corrugation 17 of the die 15, then down and up the next until in succession or at least in orderly progression each and all of them have been rolled into the metal. As this succession or. progression is carried out progressively of the covering. 11 and of the die 15, the apparatus is angularly adjusted progressively about its axes 22 to permit roller 25 always to operate in the vertical plane 28 of the axis 22, thereby insuring a more efiicient resolution of forces in the apparatus and in the material being operated upon. The corrugations being all rolled in, roller 25 and shaft 24 are removed, clamp 16 loosened, and the formed covering 11 removed. The covering is then subjected to heat treatment. especially in the instance of formation of duralumin, to the end of improving its physical properties and properly conditioning it to take the strains of usage. As a final step, it is applied to the framework 10 and fastened in place by devices 14 -or their equivalent.

section of the roller 25 fits complementally the formed corrugation. It also clearly emphasizes the uniform cross section of the corrugations as formed in the covering material 11 and the variation of the width of cross section of the corrugation with the variation in the perimeter of the body being constructed.

That our invention is susceptible of modifications goes almost without saying in view of the fact that the forms of aircraft bodies are varied in detail and in general to so considerable an extent and vary so widely in their dimensional interrelations. The annexed claims should be interpreted therefore in the light of the generic spirit of our invention as circumscribed by the prior art rather than by the circumstantial terminology of the specification and claims.

What we claim as new and useful and desire to protect by Letters Patent is 1. An aircraft body comprising an interior framework varying in perimeter with the length of the body, and a corrugated covering therefor having longitudinally extending corrugations of uniform transverse curvature throughout the length of the corrugations but varying in transverse extent of cross section proportional to the variation in the perimeter of the body along its length.

2. An aircraft body having an interior framework of longitudinall varying perimeter, an exterior covering therefor of longitudinally corrugated material, the corrugano tions of which are transversely arcuate in form and of uniform radius throughout the length of the corrugations and continuous throughout the length of the main portion of the body.

3. An aircraft body comprising an interior framework having a perimeter which varies in the lenith of the body, and an external covering t erefor of longitudinally corrugated material, the corrugations of which are arcuate in form and ofuniform radius throughout the length of .the corrugations and vary in arcuate extent in proportion to {:18 body perimeter with the length of the ody. I

In testimony whereof. they hereunto aflix their signatures.

JOSEPH LEDWINKA. EARL J. w. RAGSDALE. 7 1 30 

